This invention relates in general to vehicles for transporting concrete, and more particularly to hoppers through which the mixer units of such vehicles are loaded with concrete.
The typical mixer unit for a concrete transport vehicle has a large drum that rotates about an inclined axis, this drum being larger at its lower end than at its upper end and further having an opening at its upper end. In addition, the typical mixer unit has a hopper located adjacent to the opening at the upper end of the drum for directing concrete mix from a loading facility into the drum. Immediately below the hopper, the vehicle is also provided with a discharge chute into which the drum discharges the concrete so that it may be directed to a desired location at a construction site. Of course the vehicle has a mechanism for rotating the drum, and when turned in one direction the drum merely churns the concrete mix so that it does not set. However, when turned in the opposite direction, the drum pumps the concrete into the discharge chute which in turn directs it to the desired location.
While all mixer units are basically the same, they are manufactured in a wide range of capacities, and generally speaking the height of the transport vehicle increases with capacity. As a consequence, the loading facilities are constructed to accommodate the largest, or more accurately the tallest, of the vehicles.
In this regard, the typical loading facility is usually a drive-through arrangement which enables the hopper on the mixer unit of the vehicle to be brought into alignment with an elevated chute at the facility. The concrete mix flows out of this chute and into the hopper, which in turn directs the mix into the drum. With vehicles of large capacity, the hopper locates close to the lower end of the elevated chute at the facility, and little if any concrete is lost. In the case of vehicles with small capacity, the vehicle hopper is often considerably below the elevated chute at the facility, and this makes it difficult for the driver to align the hopper with the elevated chute. Also, even when properly aligned, wind has a tendency to blow the mix away from the hopper as the mix passes between the lower end of the chute and the upper end of the hopper. Some smaller capacity vehicles overcome this problem with hoppers of extended height. These hoppers project considerably above the highest portions of their respective drums, and in effect extend the height of the smaller capacity vehicles to that of the larger capacity vehicles. This, however, eliminates one major advantage of the smaller capacity vehicles, namely the ability to bring concrete to areas where the overhead clearance is relatively low.
For example, most manufacturing plants and warehouses of current construction are only a single story high and have concrete slabs for floors. These floors are usually poured after the walls and roof of the building have been erected, and is is not unusual for the ceiling to be at a height incapable of accommodating large capacity transport vehicles. Thus, it is desirable to bring the concrete to the site in a vehicle of small capacity that has its hopper low enough so as not to interfere with the ceiling.